4d01146f16
1. Adds support for Reset calls in AGC2. The AGC will be reset during analog gain changes. 2. Allows AdaptiveModeLevelEstimator to return estimates > 0. This can happen if the signal gain is too high. It's needed for letting the analog AGC know that the gain is too high. Bug: webrtc:7494 Change-Id: I38def17c21cc01c36aaea79a2401d8c2f289407b Reviewed-on: https://webrtc-review.googlesource.com/79360 Commit-Queue: Alex Loiko <aleloi@webrtc.org> Reviewed-by: Ivo Creusen <ivoc@webrtc.org> Cr-Commit-Position: refs/heads/master@{#23805}
114 lines
4.2 KiB
C++
114 lines
4.2 KiB
C++
/*
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* Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "modules/audio_processing/agc2/adaptive_digital_gain_applier.h"
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#include <algorithm>
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#include "common_audio/include/audio_util.h"
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#include "modules/audio_processing/agc2/agc2_common.h"
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#include "modules/audio_processing/logging/apm_data_dumper.h"
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#include "rtc_base/numerics/safe_minmax.h"
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namespace webrtc {
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namespace {
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// This function maps input level to desired applied gain. We want to
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// boost the signal so that peaks are at -kHeadroomDbfs. We can't
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// apply more than kMaxGainDb gain.
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float ComputeGainDb(float input_level_dbfs) {
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// If the level is very low, boost it as much as we can.
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if (input_level_dbfs < -(kHeadroomDbfs + kMaxGainDb)) {
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return kMaxGainDb;
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}
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// We expect to end up here most of the time: the level is below
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// -headroom, but we can boost it to -headroom.
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if (input_level_dbfs < -kHeadroomDbfs) {
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return -kHeadroomDbfs - input_level_dbfs;
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}
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// Otherwise, the level is too high and we can't boost. The
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// LevelEstimator is responsible for not reporting bogus gain
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// values.
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RTC_DCHECK_LE(input_level_dbfs, 0.f);
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return 0.f;
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}
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// We require 'gain + noise_level <= kMaxNoiseLevelDbfs'.
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float LimitGainByNoise(float target_gain,
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float input_noise_level_dbfs,
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ApmDataDumper* apm_data_dumper) {
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const float noise_headroom_db = kMaxNoiseLevelDbfs - input_noise_level_dbfs;
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apm_data_dumper->DumpRaw("agc2_noise_headroom_db", noise_headroom_db);
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return std::min(target_gain, std::max(noise_headroom_db, 0.f));
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}
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// Computes how the gain should change during this frame.
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// Return the gain difference in db to 'last_gain_db'.
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float ComputeGainChangeThisFrameDb(float target_gain_db,
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float last_gain_db,
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bool gain_increase_allowed) {
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float target_gain_difference_db = target_gain_db - last_gain_db;
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if (!gain_increase_allowed) {
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target_gain_difference_db = std::min(target_gain_difference_db, 0.f);
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}
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return rtc::SafeClamp(target_gain_difference_db, -kMaxGainChangePerFrameDb,
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kMaxGainChangePerFrameDb);
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}
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} // namespace
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AdaptiveDigitalGainApplier::AdaptiveDigitalGainApplier(
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ApmDataDumper* apm_data_dumper)
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: gain_applier_(false, DbToRatio(last_gain_db_)),
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apm_data_dumper_(apm_data_dumper) {}
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void AdaptiveDigitalGainApplier::Process(
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float input_level_dbfs,
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float input_noise_level_dbfs,
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const VadWithLevel::LevelAndProbability vad_result,
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AudioFrameView<float> float_frame) {
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input_level_dbfs = std::min(input_level_dbfs, 0.f);
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RTC_DCHECK_GE(input_level_dbfs, -150.f);
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RTC_DCHECK_GE(float_frame.num_channels(), 1);
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RTC_DCHECK_GE(float_frame.samples_per_channel(), 1);
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const float target_gain_db =
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LimitGainByNoise(ComputeGainDb(input_level_dbfs), input_noise_level_dbfs,
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apm_data_dumper_);
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// Forbid increasing the gain when there is no speech.
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gain_increase_allowed_ =
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vad_result.speech_probability > kVadConfidenceThreshold;
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const float gain_change_this_frame_db = ComputeGainChangeThisFrameDb(
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target_gain_db, last_gain_db_, gain_increase_allowed_);
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apm_data_dumper_->DumpRaw("agc2_want_to_change_by_db",
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target_gain_db - last_gain_db_);
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apm_data_dumper_->DumpRaw("agc2_will_change_by_db",
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gain_change_this_frame_db);
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// Optimization: avoid calling math functions if gain does not
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// change.
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if (gain_change_this_frame_db != 0.f) {
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gain_applier_.SetGainFactor(
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DbToRatio(last_gain_db_ + gain_change_this_frame_db));
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}
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gain_applier_.ApplyGain(float_frame);
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// Remember that the gain has changed for the next iteration.
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last_gain_db_ = last_gain_db_ + gain_change_this_frame_db;
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apm_data_dumper_->DumpRaw("agc2_applied_gain_db", last_gain_db_);
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}
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} // namespace webrtc
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